Sealing system in which there is relative sliding motion between a gate and a port

ABSTRACT

A sealing system includes a gate ( 2 ) which is pivotably mounted to a crank ( 3 ) which is mounted for rotation with shaft ( 1 ). A spring ( 5 ) is disposed between gate ( 2 ) and crank ( 3 ). The gate ( 2 ) includes an O-ring ( 6 ) which compresses and slides during closure.

TECHNICAL FIELD

This invention relates to a sealing system.

This invention has particular but not exclusive, application to sealingsystems for chambers adapted to be evacuated. This invention is hereinillustrated in the context of a sealing system for an evacuatableairlock which acts as an antechamber for a vapour deposition chamber.However, it will be understood that the invention is not limited to thisparticular environment.

BACKGROUND ART

Many different sealing systems exist for enabling evacuation of air fromvacuum chambers whilst closed, yet enable items to be introduced to orremoved from the vacuum chamber whilst open.

Disadvantages with known sealing systems range from high cost and poorreliability to large size where limited space is available.

DISCLOSURE OF INVENTION

This invention in one aspect resides in a method of sealing a porthaving a sealing face with a gate having a complementary sealing face,the method including:

abutting the gate's sealing face with the port's sealing face andtranslating the gate's sealing face relative to the port's sealing facein a direction parallel to the port's sealing face.

In the preferred embodiment the abutment of the sealing faces and thetranslation of the gate's sealing face relative to the port's sealingface occur simultaneously, although they could be sequential movements.

In the preferred embodiment the gate's sealing face approaches theport's sealing face during closing in a direction which includesorthogonal and parallel components relative to the plane of the port'ssealing face.

The gate's sealing face or port's sealing face will normally include aresilient member and the resilient member will slide or distort duringthe relative translation of the sealing faces. In the preferredembodiment, the resilient member is an O-ring which forms part of thesealing face of the gate.

In a second aspect the invention resides in a sealing system including:

gate having a sealing face; and

a port having a complementary sealing face, wherein, upon closing, therespective sealing faces abut and the gate's sealing face translatesrelative to the port's sealing face in a direction parallel to theabutting sealing faces.

Preferably, one of the sealing faces includes a resilient member andpreferably the resilient member is an O-ring. The relative translationbetween the abutting sealing faces causes sliding or distortion of theO-ring which facilitates improved sealing.

Preferably, the gate is pivotably mounted via a mobile pivot axis to acrank member which, in turn, is pivotably mounted about a fixed pivotaxis, the mobile pivot axis and fixed pivot axis being substantiallyparallel.

Preferably, the fixed pivot axis is parallel to and spaced from theplane of the sealing face of the port.

Preferably, during closing, the mobile pivot axis moves in a directionwhich includes orthogonal and parallel components relative to the planeof the port's sealing face.

Preferably, the crank member is pivoted in a first rotational directionabout the fixed pivot axis during closure and the gate member is biasedrelative to the crank member in the first rotational direction.

In another aspect the invention resides in a gate adapted to be rotatedin a first direction to sealably cover an aperture, the gate beingpivotably mounted to a crank which is pivotably mounted about a fixedaxis.

Preferably, a biasing member is disposed intermediate the crank and gatefor biasing the gate in the first direction relative to the crank.

BRIEF DESCRIPTION OF DRAWINGS

In order that this invention may be more easily understood and put intopractical effect, reference will now be made to the accompanyingdrawings which illustrate a preferred embodiment of the invention,wherein:

FIG. 1 is a cross-sectional view of the gate of the sealing system inits closed position.

FIG. 2 is a cross-sectional view of the gate of the sealing system inits open position.

FIG. 3 is a frontal elevation of the gate of the sealing system in itsclosed position.

BEST MODE

The invention is illustrated in the context of a sealing system for avapour deposition process which occurs in the presence of a vacuum. Thearticles being coated may be printed circuit boards and the port isaccordingly illustrated as being relatively long and narrow.

With reference to the FIGS, shaft 1 is rotatably mounted in bearingblocks 10 for rotation about a fixed axis in response to input via gear11. Due to the relative length of the port the shaft is of substantialdiameter to resist deflection which would compromise sealing.

Cranks 3 are fixed to shaft 1 and accordingly rotate with shaft 1. Gateplate 2 is rotatably mounted to cranks 3 via pivot pins 4 which define amobile axis.

Spring 5 biases gate plate 2 in a counter-clockwise direction relativeto cranks 3 as shown in FIGS. 1 and 2.

It will be noted that the sealing face of the port is provided byhardened sealing plate 7 and that the sealing face of the gate includesa resilient member in the form of O-ring 6. The hardened sealing platemay be replaced if its surface becomes scratched or worn. The hardenedsealing plate 7 is removably mounted to the chamber wall 9 and a furtherO-ring 8 is provided to seal between the hardened plate 7 and chamberwall 9.

Gate plate 2 has a groove shaped to hold the O-ring 6 captive.Alternatively, an O-ring clamping plate may be provided which simplifiesthe installation and removal of the O-ring. The O-ring is relativelylarge in diameter so as to provide a large sealing surface to fullyenclose small surface particles and still provide a good vacuum seal.

The open configuration is shown in FIG. 2. To close the sealing system,the entire gate assembly is rotated in the counter-clockwise directionabout the fixed axis defined by shaft 1. It will be recalled that thegate plate 2 is biased in the counter clockwise direction relative tothe crank 3. This means. that the leading edge of the gate plate 2 (orheel of the gate plate) is initially held clear of the hardened plate 7during closing. As a result, the trailing edge (or toe of the gateplate) makes first contact with the hardened plate 7. Thereafter, thegate plate 2 rotates clockwise relative to the crank against the springbias so that the gate plate squarely abuts the hardened plate. Morespecifically, the O-ring squarely abuts the hardened plate 7. Due to thecompressibility of the O-ring the gate continues to close a littlefurther. It should be appreciated that at this time the gate plate 2continues to approach the port in a direction which includes componentswhich are parallel and orthogonal to the sealing face of the port. Theorthogonal component causes compression of the O-ring between the gateand port. The parallel component causes a sliding of the O-ring relativeto the hardened plate which has a cleaning or sweeping effect.Specifically, microscopic debris particles are swept ahead of the O-ringallowing a better seal between the O-ring and hardened plate.

The preferred embodiment of the present invention provides a sealingsystem which is compact, reliable and inexpensive.

It will of course be realised that whilst the above has been given byway of an illustrative example of this invention, all such and othermodifications and variations hereto, as would be apparent to personsskilled in the art, are deemed to fall within the broad scope and ambitof this invention as is herein set forth.

The claims defining the invention are as follows:
 1. A sealing systemincluding: a fixed port having a planar sealing face; and a mobile gatehaving a complementary sealing face bearing a resilient sealing member,the mobile gate being mounted via a mobile pivot axis to a crank memberwhich, in turn, is pivotably mounted about a fixed pivot axis, themobile pivot axis and fixed pivot axis each being parallel to and spacedfrom the planar sealing face of the fixed port, the fixed pivot axisbeing spaced from the planar sealing face of the fixed port by a firstdistance, measured perpendicularly from the planar sealing face of thefixed port, that is greater than a second distance, measuredperpendicularly from the planar sealing face of the fixed port, that themobile pivot axis is spaced from the planar sealing face of the fixedport when the mobile gate closes the fixed port, such that when themobile gate engages the fixed port the mobile pivot axis and mobile gatemove in a direction which includes a component which is parallel to theplanar sealing face of the fixed port such that the resilient sealingmember slides on the planar sealing face of the fixed port, andfurthermore wherein means for resiliently biasing the mobile gate topivot about the mobile pivot axis is disposed coaxial with the mobilepivot axis and between the mobile gate and crank member such that themeans for resiliently biasing yield during closing of the fixed portwith the mobile gate.
 2. A sealing system as claimed in claimed 1,wherein the crank member is pivoted in a first rotational directionabout the fixed pivot axis as the mobile gate moves from an openposition to the position where the mobile gate closes the fixed port andthe mobile gate is biased relative to the crank member in the firstrotational direction by the means for resiliently biasing.